At sites of mining, quarrying, construction work, or the like, drilling devices, such as a crawler drill, are used to drill blast holes in rock. On a drilling device, a rock drill (drifter) is mounted on a guide shell. Rock drills are grouped into hydraulic drifters and pneumatic drifters depending on driving fluid used. A rock drill is provided with a striking mechanism and a rotating mechanism and is loaded with a rod at the tip of which a bit is attached.
In the drilling of the rock drill, a blow is given to the bit at the tip of the rod by means of the striking mechanism to produce a shock wave, while rotating the bit at the tip of the rod by means of the rotating mechanism to change the phase of the bit that contacts bedrock to apply the shock wave to the bedrock and break up the bedrock. Since the tip of the bit crushes rock to produce cuttings during the drilling, the rock drill performs flushing (removal of cuttings).